Many automotive vehicles have displays that display video, such as screens of infotainment units. Many automotive vehicles also have back-up cameras that view an area behind the vehicle which can then be displayed on the display in the vehicle when desirable. Typically, this occurs when the vehicle is in reverse. Many automotive vehicles also have obstruction sensors, such as LIDAR sensors associated with one or more sides of the vehicle (such as front, back, right, left, front right, back right, front left and back left sides) of the vehicle, that sense how far that particular side of the vehicle is from an object. These sensors are typically part of advanced driver assistance systems, commonly known as ADAS. In vehicles having obstruction sensors, when the side of the vehicle with which one of the obstruction sensors is associated approaches within a predetermined distance of the object, an alert is given to the driver of the vehicle, such as an audible alert, a visual alert, or both. The visual alert may be a graphic displayed on the display of the vehicle, such as a yellow or red line, the illumination of a discrete visual indicator such as a LED, or both. Moreover, in some vehicles, multiple alerts are given, such as a “yellow” alert when the side of the vehicle comes within a first predetermined distance of the object and a “red” alert when the vehicle comes within a second, closer predetermined distance of the object. In some cases, the obstruction sensors include rear facing obstruction sensors that sense objects behind a vehicle in an active rear sense area. As used herein, the active rear sense area is the area behind the vehicle in which the rear facing obstruction sensor can detect an object. A rear facing obstruction sensor is typically active when the vehicle is in reverse. As the vehicle moves in reverse, an alert is given if the rear facing obstruction sensor senses that the rear of the vehicle has approached too close to an object in the active rear sense area.
As discussed, in vehicles having back-up cameras, the area behind the vehicle is displayed on a display in the vehicle when the vehicle is in reverse. The back-up camera has an active rear view area which as used herein, is an area behind the vehicle that the back-up camera “sees.”
As used herein, the current road grade is the grade of the road that the vehicle is currently on and is an angle with respect to horizontal, which can be positive, negative or zero. A positive angle is when the road grade inclines upwardly with respect to the direction that the vehicle is traveling in reverse, a negative angle is when the road grade inclines downwardly with respect to the direction the vehicle is traveling in reverse, and a zero angle is when the road grade is flat. Since the rear facing obstruction sensor (or sensors) and the back-up camera are typically affixed to the vehicle, the active rear sense area and the active rear view area will change when the vehicle is approaching a change in road grade. When the change in road grade is a positive road grade change, this can trigger false obstruction alerts due to the active rear sense area changing relative to the current road grade, as discussed in more detail below. A positive road grade change is when the angle between the current road grade and the approaching road grade is positive and the approaching road grade is more upward with respect to the current road grade. This includes, without limitation: (i) when the current road grade is inclined downwardly, the approaching road grade is also inclined downwardly but at a lesser incline, the approaching road grade is flat, or the approaching road grade is inclined upwardly; (ii) when the current road grade is flat, the approaching road grade is inclined upwardly; (iii) when the current road grade is inclined upwardly, the approaching road grade is also inclined upwardly but at a greater incline.
The change in the active sense area when the vehicle is approaching a positive road grade change can result in false alarms that the rear of the vehicle is too close to an object. For example, the change in the active rear view sense area when the vehicle is approaching the positive road grade change can result in an object such as a tuft grass being in the active rear sense area resulting in an alert. If the approaching road grade was even relative to the current road grade or angles downwardly with respect to the current road grade (i.e., the change in road grade is a negative road grade change), the tuft of grass would be below the active rear sense area and thus not detected by the rear facing obstruction sensor.